Recently, much attention has been attracted to electrochemical cells, such as electronic papers, electric double layer capacitors, dye-sensitized solar cells, lithium-ion cells or light control glasses. In the electrochemical cells, there is a method of producing each cell by sandwiching a polyvinylidene-fluoride—hexafluoropropylene copolymer (PVdF-HFP) gel electrolyte membrane between electrode films.
FIG. 19 shows a structure of a dye-sensitized solar cell as an example of a conventional electrochemical cell. An example of a working electrode film 7 includes a titanium-oxide electrode formed on a glass plate. An example of a counter electrode film 1 includes a platinum electrode formed on a glass plate. A gel electrolyte membrane 10 formed of PVdF-HFP gel is sandwiched between the working electrode film 7 and the counter electrode film. A sealing material 23 is placed in the circumference of this gel electrolyte membrane 10.
PVdF-HFP gel having a solid content of 50% still exhibits a superior characteristic such that ionic conductivity of the PVdF-HFP gel is not greatly impaired. PVdF-HFP gel is used for producing an electrochemical cell having a rigid electrode has been reported demonstrate in the laboratory (refer to Patent Document 1 and Non-patent Document 1, for example).
[Patent Document 1] Japanese laid-open patent publication No. 2003-16833
[Nonpatent Document 1] “Advanced Technologies for Polymer Battery” CMC Publishing Co. Ltd, under the supervision of Noboru Oyama